A first phase of crucial talks between Iran and the International Atomic Energy Agency (IAEA) has ended in Tehran, with the Iranians optimistic about the outcome.

Iran's ambassador to the IAEA, Ali Akbar Salehi - who is in Tehran for the talks - told the BBC that agreement and mutual understanding had been reached on a plan of action to clarify the issues of concern to the agency.

The aim, he said, was to speed up co-operation, so that all the questions the IAEA is asking could be dealt with as swiftly as possible.

It seems as if the great powers, and the US especially, have decided to prevent Iran's access to nuclear power

Clearly much will depend on what actually happens in the coming days, and how forthcoming and convincing the Iranians turn out to be in meeting the agency's concerns.

These include questions about how traces of highly enriched weapons grade uranium came to found at two Iranian facilities.

By the end of the month the agency wants to have a full understanding of all Iran's past and present nuclear activities so that it is in a position to certify that the country has been abiding by its obligations under the Non Proliferation Treaty.

If it cannot do that, the issue may be referred to the United Nations Security Council where Iran could face sanctions.